Motor vehicle comprising an air conditioning system

ABSTRACT

The aim of the invention is to obviate the need for rubber hoses or other flexible rubber compensation elements, which prevent the transmission of vibrations to the vehicle body. To achieve this, the pipelines of an air conditioning system including their pipe couplings ( 42 - 45 ) are configured entirely of metal with an external diameter, in relation to the compressor, of less than 11 mm on the discharge side and less than 13 mm on the suction side. A damping curvature ( 35, 36 ) is also configured in the pipelines ( 6′, 12 ′) that connect the compressor to a heat exchanger, in addition to at least one curvature ( 37 - 40 ) required by the installation geometry of the conduit system. The system is also equipped with a pipeline, designed to restrict the flow of operating fluid, said pipeline being configured as a particularly thin pipe with an internal diameter of capillary-tube type proportions, designed to restrict the flow and an external diameter ranging between 2 and 4 mm.

The invention relates to a motor vehicle with an air conditioningsystem, whose ducting connects a compressor, which is attached to theengine of the vehicle, with at least one heat exchanger, which isattached to the vehicle body, wherein the running ducting system in theengine compartment of the vehicle has a pipe curvature, which isdictated by the installation geometry in the vehicle space, at least onepart of the pipe conduit is made of metallic substance and medium fordamping of vibration is provided for avoiding transmission of vibrationsfrom the compressor to the vehicle body.

The engine of a vehicle and the compressor of an air conditioningsystem, which is attached to it, are known to produce mechanicalvibrations and pressure pulsations in flowing heat carriers (coolants)and the requirement is to prevent such vibrations from being transmittedto the body or the passenger cell of the vehicle through damping medium.The engine of the vehicle is placed for this purpose on damping bodies.Further, as per U.S. Pat. No. 5,367,883 for example, armoured rubberhoses are fitted in the pipe conduits of the ducting of the airconditioning system, said pipes leading from the compressor to a heatexchanger; thanks to their damping the pulsations through stretchingradially and along the length, the transmission of vibration isprevented from the engine and the compressor to the heat exchangers,which are fixed on one side in the front area, and on the other side inthe air conditioning box of the vehicle on the body and, thus, also tothe body. Through their flexibility, the rubber hoses further make iteasier to mount and de-mount the engine and also to lay the pipes of theducting system in the engine compartment of the vehicle.

On account of the considerable pressure prevailing in the ductingsystem, armouring of rubber hoses and their leak-proof fitting in theotherwise metallic pipe conduits through a high-pressure tube connectionat the end is, however, very cumbersome and hence costly. Besides, dueto their larger diameters, rubber hoses demand additional space insidethe engine compartment of the vehicle, making their installation moredifficult. These rubber hoses further lead to a loss of the workingmedium since these cannot be made completely diffusion proof. These alsocannot prevent the moisture in the ducting system from getting diffused,with the result that the lubricating properties of the lubricating oil,which is contained in the working medium are adversely affected. Thesedisadvantages are also mentioned in U.S. Pat. No. 5,182,922. Theapplication of flexible pipe connectors as alternatives, cannot,however, remove this deficiency completely due to the use of elasticsealing and jointing medium, which is subjected to shear forces and isalso found wanting in high pressure zones as, for example, for airconditioning systems with CO 2 (carbon dioxide) as working medium.

It is the objective of the invention to avoid the above mentioneddisadvantages and to find a suitable vehicle with an air-conditioningsystem, which, through less manufacturing costs and reduced spacerequirements, prevents transmission of vibrations to the heat exchangerof the air-conditioning system and consequently to the body of thevehicle.

As per the invention, the objective is fulfilled in such a manner thatat least one pipe conduit, which, on one side, is connected to thecompressor and, on the other, to a ducting's heat exchanger, which isattached to the vehicle body, is entirely made of metallic substance andhas an outside diameter of less than 13 mm.

It was thus found that, in spite of using a very cost effective,integral, relatively rigid metallic substance for at least one of thepipe conduits of the ducting system and designing the same for highpressures, which are common for air conditioning systems, specially withcarbon dioxide, an adequate yielding of the pipe conduits can beachieved to sufficiently dampen the vibrations being transmitted to anattached heat exchanger and therefore to the vehicle body. Due to itsintegral, relatively small diameter, for fitting of the pipe conduit,less space is required in the engine compartment on one hand and aflexibility, on the other, makes its installation in the enginecompartment easier.

It is clear that the mentioned advantages become more prominent as thesmall pipe diameter as per the invention gets smaller. As per apreferred embodiment of the invention, a particularly thin pipe conduitwith a capillary tube-like inside diameter of less than 2 mm and alength of, for example, 900 mm, corresponding with the installationgeometry, can be provided in the area of the ducting of the airconditioning system, in which a throttling of flow of its working mediumis intended in its function; with this, besides saving a throttle valve,a particularly high damping of vibrations results as well as theadvantage of its simple installation in the engine compartment of thevehicle is obtained. This configuration is also particularlyadvantageous in applying the invention to a air conditioning system,which can be switched over to a so called ‘triangle process’ whileheating up the vehicle, wherein a pipe conduit likewise leads straightfrom the compressor to a heat exchanger, which works to heat up thevehicle.

When the diameter of a fully metallic pipe conduit on the suction side,for example, is chosen in the above range as per the invention, thepipe's bendability can be lower than the more familiar rubber likehoses, in spite of its having adequate damping properties; throughforcibly bending it by hand in freeing an assembly space while mountingor de-mounting the engine of the vehicle, it could get damaged. In thiscase, in a well accessible place in the engine compartment and away fromthe necessary connection couplings for the compressor and the heatexchanger, an additional, essentially cost effective pipe joint can beplaced opposite a hose.

The integral form of the pipes, made of metal and preferably of analuminium alloy, of the air conditioning system even leads to a poorerdamping of pressure pulsations in the working medium flow of the airconditioning system; these can, however, be averted through anenlargement of cross section over a limited length in the airconditioning system in the form of, for example, a muffler soldered to apipe. Such a thing can be manufactured in a cost effective way by deepdrawing out of the same aluminium alloy, which is used for the pipes ofthe air conditioning system.

Further embodiments of the invention are described below with the helpof drawings. It is shown in:

FIG. 1: A very simplified, schematic diagram of the ducting of an airconditioning system, which is arranged in the engine compartment of avehicle.

FIG. 2: A perspective drawing of two pipe conduits of ducting of an airconditioning system as per the conventional technology.

FIG. 3: A perspective drawing of two pipe conduits of ducting of an airconditioning system as per the invention. And

FIG. 4: A perspective drawing, comparing one pipe conduit each as perconventional technology and as per the invention.

The air conditioning system 1, which is shown in FIG. 1 and is suitablefor cooling as well as heating, has conventionally a compressor 3, whichis attached to the engine 2 of the motor vehicle. During the coolingoperation, it delivers the working medium, which is preferably carbondioxide (CO₂), via a switch valve 4 in the direction of the arrow 5through a first pipe conduit 6 on the pressure side to a first heatexchanger 8, which is attached to the front side to the vehicle body 7.Through a second pipe conduit 9, it is connected to a second heatexchanger 10, which is attached to the vehicle body 7 and is placed, forexample, in the climatic chamber of the vehicle. During working,expansion of the working medium takes place in this second pipe conduit9, for which an expansion valve 11 is provided as per the currenttechnology. A third pipe conduit 12 carries the working medium back tothe compressor 3 at the suction side.

During the heating operation, which means that the valve 4 has beenswitched over, the compressor 3 delivers the working medium in thedirection of the arrow 14 through a fourth pipe conduit 15 directly to aheat exchanger 10, which is attached to the vehicle body 7; this heatexchanger can be identical with the heat exchanger 10, as mentionedearlier. During working, an expansion of the working medium takes placein this fourth pipe conduit 15 also so that in the pressure-enthalpydiagram, a triangle shaped working diagram is generated, correspondingto a so called triangle process. A further expansion valve 16 is usedhere as per the current technology.

To ensure that the vibrations of the reciprocating engine 2 as well asthe reciprocating compressor 3, which acts on, for example, the Z-crankprinciple and the pressure pulsations of the working medium of the airconditioning system do not propagate up to the heat exchangers 8 and 10and to the vehicle body 7 and consequently up to the passenger chamberof the vehicle through the first, third and fourth pipe conduits 6, 12and 15, a fibre reinforced rubber hose 17 and 18 is added respectivelyto the pipe conduits 6, 12, 15 of the popular air conditioning system 1,as is illustrated in FIG. 2, and these are connected in a leak-proofmanner to the otherwise metallic pipe conduits 23 to 26 through tubecollars 19 to 22, which are force fitted. These pipe conduits 6, 12 areconnected in a detachable manner to the compressor 3 on one side and toany of the heat exchangers 8, 10 on the other through pipe couplingelements 27 to 30 respectively at their ends.

After mounting of the engine 2 in the engine compartment 31, as one ofthe connection coupling 29 is no more accessible, a short pipe piece 32leads to an assembly-friendly position, where one more detachableconnection coupling 33 is provided. The pipe section 6 on the pressureside on the contrary, due to the flexibility of the rubber hose 17,allows itself to be bent side-wise away to a free position for mountingor de-mounting of the engine 2.

In an embodiment as per the invention and hence a completely metallicconfiguration, made of, for example, an aluminium alloy, FIG. 3illustrates the running pipe conduits 6′, 12′ between the compressor 3and a heat exchanger 8, 10 of preferably a CO₂—ducting system. Theircomparatively smaller outer diameters of less than 13 mm on the suctionside (12′) and less than 11 mm on the pressure side (6′), together withat least one pipe curvature 35, 36, lead to a sufficient amount of yieldin the pipes 6′, 12′—despite a high proof pressure strength of, forexample, 500 bar—which prevents transmission of vibrations from theengine 2 to the vehicle body 7. These pipe curvatures 35, 36 arepreferably provided additionally as damping curvatures to at least oneof the pipe curvatures 37 to 40, which are dictated by the installationgeometry of the ducting system.

For simplifying work in the engine compartment 31, including mountingand de-mounting of engine 2, an additional, easily detachable pipe joint46 and 47 is provided in each of the pipe conduits 6′ and 12′ at a largedistance from the pipe coupling elements 42 to 45 at their ends; thesepipe joints, including their sealing rings (not shown), are likewisecompletely made of metal and hence are diffusion proof.

In the illustration in FIG. 4, a configuration of the second pipeconduit (9′) as per the invention and its configuration (9) as per thecurrent state of technology are shown side by side. Since expansion ofthe working medium of the air conditioning system is to take place inthis second pipe conduit 9, which is connected to either of the heatexchangers 8, 10 through the coupling elements 48′, 49′ or 48, 49 attheir ends respectively, an expansion valve 50 is provided in this asper the current state of technology. Besides this, to the second pipeconduit 9, a rubber hose 51 is also assembled, which, through itsflexibility, makes its installation in the engine compartment 31 easierand also contributes towards damping of vibrations.

Based on a preferred embodiment of the invention, this second pipeconduit, in which a throttling of the flow of the working medium of theair conditioning system is intended in the system of working, is made asa thin pipe 9′ with a capillary tube like small inside diameter, whichis suitable for throttling of the working medium; an expansion valve 50becomes redundant in that case. The outer diameter of this pipe conduit9′, which is suitable for throttling, can thus be considerably smallerthan that of the first and second pipe conduits 6 and 12 or 6′ and 12′respectively, lying, for example, in the range of 2 to 4 mm.Consequently, this pipe conduit 9′ is particularly flexible and can befitted easily and in a space saving way in the engine compartment 31.The same holds true also for the pipe conduit 15, which is used in theheating operation of a CO₂ (carbon dioxide) air conditioning system 1,wherein the customary expansion valve 16 can be replaced by a completelymetallic, thin pipe conduit (15′) with capillary tube-like small insidediameter.

To avoid transmission of vibrations, generated due to pressurepulsations in working medium flow of the air conditioning system 1, anadditional volume can be provided further in the completely metallicpipe conduits 6′, 15′ on the pressure side or in a possibly availablepipe between the compressor 3 and the switch valve 4. Such an additionalvolume can be realized through an enlarged pipe diameter over a definitepart length or through a separate part, which is added to the pipeconduit or the pipe—the so-called muffler 52. Such an additional volumecan also be integrated with the compressor 3.

To prevent blockade through contamination in the working medium of thethin pipes 9′ and 15′, which, with their capillary tube-like smallinside diameters, act as expansion valves (11, 16), a filter 53 ispreferably provided in the relevant ducting systems, this filter forminga structural unit with the muffler 52, for example. Further, the filter53 can be combined with a homogenizer (not shown), by which, thedetrimental large gas cavities in the flow of the working medium can besplit up in a homogeneous manner.

1. Motor vehicle with an air conditioning system (1), whose ducting(6,12,15) connects a compressor (3), which is attached to the engine (2)of the vehicle with at least one heat exchanger (8,10), which isattached to the vehicle body (7), wherein the ducting system(6,9,12,15), running in the engine compartment (31) of the vehicle, hasat least one pipe curvature (37-40), which is determined by theinstallation geometry in the vehicle space, at least one part of thepipe conduits (6,9,12,15) of the air conditioning system is made ofmetallic substance and medium for vibration damping is provided to avoidtransmission of vibrations from the compressor (3) to the vehicle body(7), characterized in that at least one pipe conduit (6′, 12′, 15′),which is connected on one side to the compressor (3) and to a heatexchanger (8, 10), which is attached to the vehicle body (7) on theother, is made entirely of metallic substance, inclusive of its pipecouplings (42-45), and has an outside diameter of less than 13 mm. 2.Motor vehicle according to claim 1, characterized in that in at leastone pipe conduit (6′, 12′, 15′), which is entirely made of metal, atleast one damping curvature (35, 36) is additionally provided to atleast one pipe curvature (37-40), which is determined by theinstallation geometry in the engine compartment.
 3. Motor vehicleaccording to claim 1, characterized in that one pipe conduit (9′, 15′),in which a throttling of flow of the working medium of the airconditioning system (1) is to be provided in its functioning, is made asa thin pipe conduit (9′, 15′) with a capillary tube-like small insidediameter, which is suitable for throttling of flow.
 4. Motor vehicleaccording to claim 1, characterized in that the working medium of theair conditioning system is CO_(—)2 (carbon dioxide) and, in relation tothe compressor (3), the outside diameter of its pipe conduits is smallerthan 11 mm on the pressure side and smaller than 13 mm on the suctionside.
 5. Motor vehicle according to claim 4, characterized in that anarea of the CO_(—)2-ducting of the air conditioning system (1), in whicha throttling of flow of its working medium CO_(—)2 is to be provided, ismade as thin pipe conduits (9′, 15′) with a capillary tube like insidediameter of less than 2 mm and an outside diameter in the range of 2 to4 mm.
 6. Motor vehicle according to claim 5, characterized in that afilter (53) is added in flow direction in the ducting before the pipeconduit (9′, 15′) with capillary tube-like inside diameter.
 7. Motorvehicle according to claim 1, characterized in that at least one fullymetallic pipe conduit (6′, 12′) of the ducting has an additional pipecoupling (46, 47) at a distance away from its connection couplings(42-45) for the compressor (3) and for the heat exchanger (8,10). 8.Motor vehicle according to claim 1, characterized in that in a pipeconduit (6′), leading from the compressor (3) to a heat exchanger (8) onthe pressure side of the ducting of the air conditioning system (1), anenlargement of cross section (52) is provided for damping the pressureimpulses in the working medium flow.
 9. Motor vehicle according to claim9, charcterized in that the enlargement of cross section of the ductingin a pipe conduit, which is intended for damping the pressure impulses,is provided in the form of muffler like pipe enlargement.
 10. Motorvehicle according to claim 1, characterized in that the pipe conduits(6, 12, 15) of the ducting of the air conditioning system (1), includingtheir pipe couplings (42-49) and their sealing elements, are made fromdiffusion-proof metal.
 11. Motor vehicle according to claim 2,characterized in that one pipe conduit (9′, 15′), in which a throttlingof flow of the working medium of the air conditioning system (1) is tobe provided in its functioning, is made as a thin pipe conduit (9′, 15′)with a capillary tube-like small inside diameter, which is suitable forthrottling of flow.
 12. Motor vehicle according to claim 3,characterized in that the working medium of the air conditioning systemis CO₂ (carbon dioxide) and, in relation to the compressor (3), theoutside diameter of its pipe conduits is smaller than 11 mm on thepressure side and smaller than 13 mm on the suction side.
 13. Motorvehicle according to claim 3, characterized in that an area of theCO₂-ducting of the air conditioning system (1), in which a throttling offlow of its working medium CO₂ is to be provided, is made as thin pipeconduits (9′, 15′) with a capillary tube like inside diameter of lessthan 2 mm and an outside diameter in the range of 2 to 4 mm.
 14. Motorvehicle according to claim 11, characterized in that at least one fullymetallic pipe conduit (6′, 12′) of the ducting has an additional pipecoupling (46, 47) at a distance away from its connection couplings(42-45) for the compressor (3) and for the heat exchanger (8,10). 15.Motor vehicle according to claim 2, characterized in that at least onefully metallic pipe conduit (6′, 12′) of the ducting has an additionalpipe coupling (46, 47) at a distance away from its connection couplings(42-45) for the compressor (3) and for the heat exchanger (8,10). 16.Motor vehicle according to claim 2, characterized in that in a pipeconduit (6′), leading from the compressor (3) to a heat exchanger (8) onthe pressure side of the ducting of the air conditioning system (1), anenlargement of cross section (52) is provided for damping the pressureimpulses in the working medium flow.
 17. Motor vehicle according toclaim 3, characterized in that in a pipe conduit (6′), leading from thecompressor (3) to a heat exchanger (8) on the pressure side of theducting of the air conditioning system (1), an enlargement of crosssection (52) is provided for damping the pressure impulses in theworking medium flow.